Production of photographic color sound films



Patented July 16, 1940 UNITED, STATE -PRODUGTION F PHOTOGRAPHIC COLOR SOUND John Eggert, Leipzig,

mlus Gerd Heymer, Wolfen,

Kreis Bitter-fold, and Werner Schultze, Dessau in Anhalt, Germany, signments, toGeneral tion, New York, N. Y.

ware

assignors, by mesne as- Aniline & Film Corporaa corporation of De1a- No Drawing. Application June 19, 193'], Serial N0. 149,206. In Germany AllgllSt 14, 1936 1 Claim.

Our present invention relates to photographic sound films and more particularly to photographic 'color sound films.

One of its objects is to provide a process of producing color sound films. Further objects will be seen from the detailed specification fol-. lowing hereafter. It is, known that in certain process for producing color sound films the sound track must. receive special consideration. If the sound track has been produced in color on a colorless or colored ground the track itself must be opaque to that light for which the scanning photo-cell is sensitive and further all the remaining color layers which if desired cover the region of the sound strip in even coloration, must be fully transparent 'for this region. This is the case, for example, in so-called silver bleaching-out processes, in which the photographic layers contain dyestuffs and metallic silver or compounds of these and inwhich by treatment with certain fixing of the sound strip and then the sound- I track must be protected by a varnish impermeable to water before the treatment in the subsequent baths for bleaching the color. This process is inconvenient and very difficult to practice in the case of continuous production. Moreover, the requisite varnishing may be a source of disturbance owing to perforations in the varnished layer, whereby the bleaching-out process is not complete. and in consequence the sound track develops a discordant murmur; moreover, if the varnish dries in a wavy form or later becomes cracked like, disturbances are introduced. This invention relates to a process whereby the manufacture is simplified and' the possible sound disturbances are diminished as muchas may be, and comprises the conversion, after the production of the.silver images, of thesilver of the sound strip into a compound, which on the one hand must obviously be opaque in the region of the spectrum to which 'the scanning device is' sensitive and on the other hand must have the characteristicthat in the' following bleaching baths there is no further action on this color,

so that the application of the varnish, with its injurious consequences, is unnecessary.

For example, the following procedure may be Portion 1 Potassium ferricyanide 'grams 10 Potassium bichromate solution of 1 per cent strength cc 1.3' Water litre 1 Portion 2 Iron ammonia aluin grams' 21 Water litre 1 Portion 3 Oxalic acid 'grams 25 Water 1itre 1 ing equal volumes of Portions 1, 2 and 3. The

limitation of the action of this bath to the sound strip is secured in the known manner, that is to say the film dips in the solution only in so far as the sound strip is covered or the solution. is applied to the sound strip by means of rollers, bands ofa spongy structure, spraying nozzles or the like, care being taken that by inclination of the edge of. the film in question the solution is prevented from running over the picture strip. The Prussian Blue image thus produced is sufficiently opaque' to the infra-red for. which the photo-cells preferably used at the presenttime- .are chiefly sensitive and this coloring matter does not change in the subsequent bleaching baths;

Another example is as follows: After developing, fixing and washing of the picture strip and sound strip the latter is treated as described abovein the following solution:

, cc.- Lead nitrate solution of 10 per cent strength 15 Potassium ferricyanide solution of 10 per 'cent strength Nitric acid of 10 per cent strength.

Water After a treatment for about 5 minutes the film without being washed is transferred to a bath .of nitric acid of per cent strength and then .washed for. about two minutes and treated with I the following bath to produce an indifferent toning:

cc. Cobalt nitrate solution of 10 per cent strength 30 Potassium bromide solution of 10 per cent strength 20 Nitric acid of 10 per cent strength 1 Water 70 This toning may be applied if desired after the first development and before the first fixing if care is taken to interrupt the development by means of a suitable bath.

Since a portion of the light for which the photo-cell is sensitive is absorbed in the film containing coloring matters, particularly in the blue-green portion, it is frequently advantageous to destroy this coloring matter and particularly the blue-green color in order that the reproduction of the sound may be possible with a more feeble source of light.

For this purpose the sound. track may be produced in known manner on that side of the film which does not contain the blue-green portion and the side containing the blue-green portion is diffusely illuminated opposite the sound track so that in the bleaching bath the bluegreen coloring matter is destroyed. Instead of treating the sound strip in a bath, however, it is possible to destroy the coloring matter, particularly the blue-green portion without attacking the substance of the sound track. In this case the sound track may be either on the same side as the blue-green portion or on the opposite side.

For example, if the film carries as the bluegreen dyestufi Brilliant Benzo Fast Green after the conversion of the silver of the sound track into Prussian Blue the sound strip may be treated with a solution containing per liter of water 8 grams of potassium bichrofnate and 16 cc. of I concentrated sulfuric acid. While the Prussian Blue is not attacked by this solution the dyestufl? in the blue-green layer is very rapidly destroyed. Just as in the above described conversion of the silver of the sound track into another substance care must obviously be taken that the bath can afiect only the sound track and not the pictures.

What we claim is: A process of producing subtractive color pictures with a sound track which comprises copyout the dyestufi by means of a bath usual in silver color bleaching-out processes, and removing the superfluous silver.

' JOHN EGGERT.

GERD HEYMER. WERNER SCHULTZE. 

